Device for the pre-folding of the closure of a folding box

#The invention relates to a device for the pre-folding of a closure on a folding box which is rectangular in cross section, and especially oblong-rectangular, at least in the area of the closure, the said closure formed from the creased but unslotted end portion of the walls of the said box, two confronting closure panels being each provided with a pair of creases running from the corners and converging towards the center of the margin for the formation by folding of triangular pockets, the said device consisting of two pairs of folding tools which are placed at 90.degree. to one another, the first pair of which, associated with the end panels provided with converging creases, being movable toward or away from one another, and the other pair being movable toward one another, the said device consisting also of a plunger disposed in the center between the folding tools and adapted to the free cross section of the box, which plunger serves as a backing means in the prefolding of the closure by the folding tools.

#The pre-folding of a closure of an unfilled box serves to facilitate the later sealing of the filled box, because even with folding creases the top of the box cannot be perfectly folded and sealed when the box is full. To obviate these difficulties, it is common to pre-fold the end of the box which is provided with folding creases.

#In one known device of the kind described above, the folding tools act exclusively externally on the top portion of the box. The folding tools associated with the top panels from which the triangular pockets are made are constructed as substantially triangular plates matching the pockets, while the other two folding tools are in the form of oblong rectangular blocks. With such a device a pre-folding can be achieved which is sufficient for the final folding that comes later on. However, it is disadvantageous that the end portion of the box remains more or less in the pre-folded condition after the pre-folding. This interferes with the further processing of the box, because the plunger cannot be withdrawn from the box unless the box is held. It then scrapes the inside surface of the box, which is coated with a thermoplastic material as an adhesive for the closure.

#The invention will now be further explained with the aid of a drawing representing an embodiment, wherein

#FIGS. 1 and 2 are diagrammatic front elevational views of an inwardly prefolding device without its drive,

#FIGS. 3 and 4 are similar views of an outwardly folding device,

#Each device consists of a plunger 2 which can be introduced into a box 1 to serve as a backing means, and which for this purpose has a cross section matching the cross section of the box 1, two oblong rectangular folding tools 3 and 4 disposed on the long sides, which can be pivoted against one another, and two fork-like folding tools 5 and 6 at 90.degree. thereto, which can be pivoted toward and away from one another. The device operates in principle such that, after the plunger 2 has been introduced into the box 1 and simultaneously the fork-like folding tools 5 and 6 have been lowered astride the narrower end panels of box 1, the folding tools 5 and 6 are rocked towards the long axis of the box or away from it, so that the panels engaged by these folding tools are folded to form a triangular pocket. At the same time the folding tools 3 and 4 act on the long sides. The upper marginal portion of plunger 2 serves as a backing means during the pre-folding by the folding tools 3, 4, 5 and 6, so that the box 1 is folded along the crease on its entire periphery. After this pre-folding procedure the folding tools 3 and 4 are retracted. Since they engage only the outside of the box, they are unable to turn back the end panels of the box. The fork-like folding tools 5 and 6, however, engage the end panels and in the manner turn the end panel of box 1 to its original state, in which the internal plunger 2 can by extracted from the box 1 without the need for the box to be held.

#In order for the pre-folding and unfolding to be performed with sufficient precision and with a minimum of harm to the closure as required for a perfect final sealing of the box, the fork-like folding members 5 and 6 have preferably a certain configuration and are able to be reversed selectively for an outward folding action and an inward folding action. Details of the configuration, mounting and drive of the folding tools 5 and 6 are represented in FIG. 9. Each folding tool 7, 8, 9 and 10 has two unlike prongs or tines, namely a folding tine 7a, 8a, 9a, 10a, and an unfolding tine 7b, 8b, 9b, 10b. The opening formed between the tines and facing the edge of the box is curved against the folding direction. The degree of curvature, the size of the opening and the position of the pivots 11, 12, 13 and 14 are interrelated such that the end panels of the box which are engaged by the tines 7a-10b will be engaged only by folding tines 7a-10a throughout the entire pre-folding operation, and only by the unfolding tines 7b-10b during the unfolding operation. This is important so that the end panels will fold exclusively along the creases during the pre-folding and unfolding operations, so that the areas between said creases will remain flat.

#The pivots 11-14 of the folding tools 7-10 are mounted in a common beam 19, on which the plungers serving as backing means are also fastened by their flat stems 22 and 23. Additional bearing supports 24, 25 and 26 are fastened to beam 19 for the support of a camshaft 27 serving for the actuation of the folding tools 7-10; this camshaft is driven by a drive which will be described further on.